Half life

Half-life

Poll

How much do you already know about Half-life?

• I am new to this topic

• I know a little about this topic

• I am fairly confident in this topic

• This topic is a free A1

Chernobyl 1986

• Explosion released large amounts of radioactive material into the air.

• The site is still unsafe due to long-lasting radioactive substances like caesium-137 and plutonium-239.

What happened?

​To understand how long these radioactive substances will last, we first need to learn about half-life

​Half-life

Half life is the time taken for half the number of radioactive nuclei in a sample to decay

​t=10min

​t=10min

Multiple Choice

A radioactive rock has a half-life of 10 years.
If you start with 100 grams, how much will be left after 10 years?”

• 50g

• 100g

• 10g

• 0g

Multiple Choice

A radioactive substance has a half-life of 5 years.
You start with 80 grams.
How much will be left after 15 years?

• 30g

• 20g

• 10g

• 5g

Major radioactive substances released in Chernobyl

Open Ended

It is generally considered safe when activity falls to less than about 1% of its original level. When will Chernobyl be habitable again?

Summary